Thermostat



March 22, 1932 w OBLE 1,850,241

THERMOSTAT Filed Nov 29, 1929 Patented Mar. 22, 19 32 WARREN NOBLE, or nn'rnorr, MICHIGAN THERMOSTA'I.

Application filed. November as, 1929. Serial Ito. 410,323.

This invention relates to thermostatic switches and has for its object to provide a suitable switch of this type which will find advantageous utility particularly in connection with ovens of electrically heated stoves.

An object of the invention is to provide a sensitive thermostatic control for the switch of an electric circuit which will be operative under the influence of the changing volume of 30 gas in a small chamber exposed to heat within an oven or other container in order to make and break an electric circuit upon the attainment of heat in the oven to a predetermined degree.

A further object is to provide a yielding resistance to the making and breaking of the electric circuit which may be varied as to the relative point of yield so that the operation of the switch may be set at a plurality of points each corresponding to a difi'erent temperature to provide a variably operative device for controlling the oven over a wide heat range.

In carrying the invention into eilect, use

is made of a sealed gas chamber having an end wall capable of flexing to compensate for changes in volume of the gas in the chamber under variable heating, the chamber being placed internally of the oven, whereupon this flexing movementis translated outwardly of the oven by a link which abuts the said end wall and a switch arm, a suitable yielding means, such as a compression spring, opposes outward flexing of the end wall by contact with the switch arm and a fixed support and is variably compressible to offer a desired re sistance to movement of the link so that a suitable means adaptable for recording the degree of resistance will likewise furnish a correct indication of the temperatures at which the electric circuit controlled by the switch will be opened and closed.

Other objects may be narrated as including ease of assembly of the component parts with respect-to each other and with respect to the oven with which it functions, cheapness of manufacture, neat appearance and compactness.

Still further objects and advantages either directly described or indirectly implied will suitable fluid or gas such as hydrogen with A become apparent as reference is had to the accompanying drawings wherein is illustrated, merely by way of example, one embodiment of my invention, and in which:

Figure 1 is a front elevation of my improved thermostat switch;

Figure 2 is a transverse horizontal sectional view taken along line 2 2 of Figure 1;

Figure 3 is a vertical section taken along to the line 3 3 of Figure '2;

Figure 4 is a bottom plan view of the cap which comprises a manual setting means; an i Figure 5 is a transverse section taken along the line 5 5* of Figure 2.

7 Referring more particularly to the drawings, the numeral 1 refers to the wall or door of an oven to which it is desired to attach a thermostatic control switch which forms the subject matter of this application.

The wall 1 has a hole therethrough for the passage of a link casing 2 which extends into the oven for the reception of a flared end 3.

A cap a is crimped around the edge of the W3 flared end 3 upon the insertion of a disc 5, the crimped portion forming an air or gas tight connection for the cup. The disc 5 is a very thin metallic diaphragm which is annularly corrugated to permit of ready de- 949 formation under pressure, and is formed with a cup at its center, the axis of which is substantially coincident with the axis of the link casing 2 so that a link 7 extending through the casing 2 may be supported by the cup. $5 lhe edges of the disc 5 are rigidly fixed, as by welding or in any suitable manner to form a gas-tight joint for the purpose of sealing a which the cap 4 is filled. The cap may be filled through a hole which is then sealed by a plug 8.

The outer end of the link casing 2 is flared widely at 9 in order to receive electric wiring and terminals as more clearly shown in Figure 3 wherein two double leads 10 and 11 lead respectively from a suitable source of electric power and to the oven heating element or other suitable mechanism for controlling the oven heating element. The lead Mm trical connection to a switch 13 secured thereinteriorly of the oven to overcome this comment with a terminal 15 which establishes an electrical circuit through a second post 16 and out through the line 11 to the oven heating element, relay or motor (not shown). A cup 17 is fixed to the switch 13 at the center thereof which is also the center of the bore of the casing 2 and forms a support for the outer end of the link 7 so that it is held in suspended relation with respect to the casing 2. It will thus be seen that if the oven is heated interiorly the gas in the cap 4 will be likewise heated and will increase in volume in accordance with Boyles law, causing distension of the disc 5 and outward displacement of the link 7 which in turn is so supported as to control the electrical circuit to the oven heating element. It remains, then, to provide a means for determining at what temperature or temperatures the circuit will be closed which will be hereinafter discussed.

A housing 18 for the wiring, etc., is formed with an inside diameter at its outer end substantially equal to that of the flared end 9 and is provided with a shoulder 19 against which the end 9 abuts. A groove for containing a spring ring 20 is so placed as to main tain the end 9 snared against the shoulder 19 to form a retaining means for the housing 18. This housing may be described as having substantially a truncated cup shape having an opening through the base thereof for insertion of a cap 21. This cap is provided with a plurality of prongs 22 for abutment against the interior of the rim of the axial opening upon which a cam surface 23 is formed whereupon rotation of the cap 21 causes an inward and outward displacement thereof with respect to the fixed flared end 9 and the cup 17.

The cap 21 carries a disc 24 which forms an abutment for a spring 25 which is supported at its other end on a flange of the cup 17. This spring is in direct opposition to the disc 5, and will restrain any outward distension of the disc in accordance with the degree of compression imparted thereto by rotation of the cap 21. Thus if the comparative displacements are computed to give,a desired range of compression, a notch or mark 26 on the cap 21 will indicate the amount of compression in accordance with an angle traversed by rotation thereof and indications corresponding to the degrees of heat necessary pression whereby the switch will operate to break and make the circuit and may be placed on the cap adjacent the mark 26. Thus the numerals illustrated represent hundreds of degrees, the setting shown representing a displacement of the cap 21 and hence compression on the spring 25 of an extent which will require that the oven attain a temperature of 425 in order to actuate the switch 13.

Instead of the arrangement shown, it is obvious that by reversing the terminals 1e, 15 the same arrangement could be employed to close the circuit as desired, in which case the lead 11 instead of leading to the oven heating element might go to a relay or to a small motor which would act to break the circuit to the oven element. This arrangement would be desirable in case of heavy loading wherein arcing at the terminals is of consequence and since it requires only a slight change in the arrangement shown, is mentioned as being of preferred form in certain cases.

While I have described my invention with great particularity with reference to a particular illustration, it will be obvious that many slight changes and various modifications therein might be made without departing from the spirit of my invention, and I, therefore, desire to be limited in application and construction thereof only by the scope of the appended claims, wherein:

What I claim is:

1. In combination with a thermostatic switch, a switch arm having a cup fixed therein, a gas chamber having a flexible end wall capable of distending to compensate for the change in volume of the gas in said chamber under varying temperatures,'a cup in said end wall and a link having one end supported in the cup in said end wall and the other end supported in the cup of said switch arm whereby distension of said end wall under a rise of temperature of said gas actuates said switch arm in one direction, yieldin means resisting outward displacement of said link, and means for varying the compression of said yielding means to vary the temperatures under which said swiltich will close under actuation of said end wa 2. In combination with a thermostatic switch, a switch arm having a cup fixed therein, a gas chamber having a flexible end wall capable of distending to compensate for the change in volume of the gas in said chamber under varying temperatures, a cup in said end wall and a link having one end supported in the cup in said end wall and the other end supported in the cup of said switch arm whereby distension of said end wall under a rise of temperature of said gas actuates said switch arm in one direction, yielding means resisting outward displacement of said link, a housing-for said yielding means, an abutment for said yielding means comprising a manually rotatable knob having lugs thereon, a

a cam surface on said housing supporting said lugs whereby rotation of said lugs will cause inward and outward displacement of said knob corresponding to the pitch angle of said cam, whereby the compression of said spring may beset for a predetermined degree of resistance to movement of said link and closing of said switch by said end wall.

3. In combination with a thermostatic switch, a switch arm having a cup fixed therein, a gas chamber having a flexible end wall capable of distending to compensate for the change in volume of the gas-insaid chamber under varying temperatures, a cup in said wall and a link having one end supported in the'cup insaid end wall and the other end supported in the cup of said switch arm whereby the distension of said end wall under a rise of temperature of said gas actuates said switch arm in one direction, yielding means resisting outward displacement of'said link, a housing for said yielding means, an abutment for said yielding means comprising a manually rotatable knob having lugs thereon, a cam surface on said housing supporting said lugs whereby rotation of said lugs will cause inward and outward displacement of said knob corresponding to the pitch angle of said I cam, whereby the compression of said yielding means may be set for a predetermined degree of resistance to movement of said llnk and closing of said switch by said end wall,

and means for indicating the degrees of compression which may be imparted to said yieldrounding medium, switch means supported on the other of said flanges for opening and closing an electrical circuit, and means in said passageway for actuating said switch means i in response to the changes in said thermostatic element.

5. In a thermostatic control mechanism, a member arranged to extend through an opening in a supporting structure such as a wall, a flange formed on said member extending over the forward surface of said wall, switch means supported on said flange, a housing for said switch means extending over the periph eral edge of said flange into engagement with said wall, said housing being secured to said flange, a thermostatic element responsive to temperature changes, said element being connected to the other end of said member for movement towards and away from the other surface of said wall, said element, flange and. housing cooperating to clampingly engage the surfaces of said Wall, and means connecting said switch means and element whereby said switch means will be actuated in response to the changes in said thermostatic element.

6. In a thermostatic control mechanism, a member arranged to extend through an opening in a supportingstructure such as a wall, a flange formed on said member extending over the forward surface of said wall, switch means supported on said flange, a housing for said switch means extending over the peripheral edge of said flange into engagement with said wall, said housing being secured to said flange, a thermostatic element changeable with temperature variations, said element being in threaded engagement with the other end of said member to enable its being tightened against the rear surface of said wall, whereby said flange and housing will be forced against the forward surface of said wall, and means connecting said thermostatic element and switch in such a manner that the latter will respond to changes in the former due to variations in temperature.

7. In a thermostatic control mechanism, a member arranged to extend through an opening in a supporting structure such as a wall, a flange formed on said member extending over the forward surface of said wall, switch means supported on said flange, a housing for said switch means extending over the peripheral edge of said flange into engagement with said wall, said housing being secured to said flange, a thermostatic element responsive to temperature changes, said element being connected to the other end of said member for movement towards and away from the other surface of said'wall, said element, flange and housing cooperating to clampingly engage said wall, means for actuating said switch means in response to the changes insaid thermostatic element, and means adjustable from the exterior of said housing including a resilient connection to said switch means for varying the actuation of said switch means relative to the changes in said thermostatic element.

In testimony whereof I aflix my signature.

WARREN NOBLE. 

